1. Field of the Invention
The present invention relates to a gateway system for a voice communication between terminals connected with the Internet, and more particularly, to a gateway system for voice communication in which a voice signal transmitted from terminals are compressed to be transmitted to the Internet and the compressed voice signal transmitted from the Internet is uncompressed to be transmitted to the terminals, thereby enabling voice communication between terminals. The invention also relates to a controlling method of the gateway system.
2. Description of the Background Art
Generally, there are two communication methods: a voice communication method applied between terminals (i.e., telephone or facsimile, etc.) connected with a public switch telephone network (PSTN) and a data communication method applied between terminals (i.e., Internet phone, personal computer, etc.) connected with a local area network (LAN) that is connected with the PSTN or with a dedicated network.
Recently, as communication equipment and techniques are being progressed, the voice communication and the data communication are made through a single communication network. That is, an Internet phone and a PC are respectively connected with the LAN connected with Internet protocol-based Internet, so that voice communication is made through the internet phone while data communication is made through the PC.
Generally, communication protocols such as a ring signal period and a communication system between exchanges are differently set according to regions or nations. But, in case of the Internet phone connected with the Internet on the basis of the Internet protocol (TCP/IP), since voice communication is performed through the Internet, without requiring the PSTN for use only for voice communication, regardless of a private branch exchange (PBX) pursuant to the communication protocols, no expense incurs with respect to maintaining and managing the PSTN.
In a situation with the network formed as described above, in order to perform voice communication through the Internet on a real time basis, the voice signal is to be compressed and packetized to a small size and then transmitted to the Internet, and the compressed voice signal as received from the Internet is to be restored to its original voice signal. In this respect, a CODEC for performing a function to compress the voice signal and restore the compressed voice signal to its original signal must be installed at the Internet phone.
The communication protocols for the voice communication through the Internet includes recommendation H.323 incorporated by ITU-T (International Telecommunication Union-Telecommunication Standardization Sector), and the recommendation H.323 uses recommendation Q.931 for connection establishment. Developed for ISDN (Integrated Services Digital Network), the recommendation Q.931 processes the voice signal as well as a call in the Internet phone itself.
A recently developed multimedia Internet protocol system (MIPS) to support the recommendations H.323 and Q.931 of the protocols and enable communications through the Internet includes a gateway system enabling communication between Internet phones by transmitting a voice signal packet through the Internet.
However, when the Internet phone connected with the gateway system of the conventional art constructed as described above is desired to communicate with other Internet phone, a voice signal should be compressed and packetized by a CODEC installed in the Internet phone itself to be transmitted, and the compressed voice signal should be received and restored to its original voice signal.
Therefore, the gateway system in accordance with the conventional art is disadvantageous in that since the voice signal is processed by the CODEC installed in the Internet phone no matter that the Internet phone communicates with an Internet phone or a telephone set located in a remote place through the Internet or that the Internet phone communicates with other Internet phone commonly connected with a single LAN, the voice communication between the Internet phones is not performed on a real time basis. Moreover, only the Internet phone including the CODEC can perform voice communication.